Much missed, by satirists at least, former US Defence Minister, Donald Rumsfelt, was trying to sum it up in his famous plate of verbal spaghetti about things we know and things we don't know we know. Perhaps his intellectual superior, Homer Simpson had it more succinctly in his universal comment on the human condition: "doh".It is the matter of spelling out the blindingly obvious; the failure to see the woods for the abundance of trees.As I have spent a little over ten per cent of my life in the digital world, I still have a healthy sceptical view of what appears or what appears to be, in cyberspace, as opposed to what really exists in the actual world.It is a continuous thread in these columns as they have progressed over the years in the challenge to transfer an image from reality, into algorithms, and back to reality in the form of printed matter, or representation on assorted materials.There are, as we know to our costs, lots of issues in colour management, and media profiles, much discussed already, but there are also things that are sometimes more basic. Some things are so basic that they are too obvious to be spotted.Perspective is one of those wonderful basics. It is both an intelligent observation, and an actual optical phenomenon.Our complimentary eyes allow us to judge the size and shape of objects, and their relative distance. This was vitally important, for example, to work out just how far away the sabre toothed tiger was, and therefore those of our ancestors with a good sense of perspective were able to evolve, while others became part of the food chain.When man first starting putting pictures on cave walls, they were very basic and flat, hardly surprising with the limited materials available. This two dimensional art continued, in Europe at least, right up until the Middle Ages.It was the explosion of intellectual and technical discovery that was the Renaissance which brought amongst many wonders, images that had the appearance of three dimensional depth and perspective. As scientists and philosophers pushed the boundaries of knowledge, artists pushed the boundaries of painting. As with the present digital revolution, and the previous industrial revolution, practical technical advances could be used to expand the potential of art, entertainment and education.With all of the technology we have at hand today, I am regularly disappointed at the output we have to manage at the print shop. Perhaps it is an inevitable consequence of the empowerment of the many allowed by the computer, that design and imagery are no longer the sole department of the talented. The one most significant difference with the digital revolution is that so much of it is created or manipulated in an artificial environment rather than the real one, and that can distort perspective as well as size and hue. The dilemma of print on demand is translating that creation of binary language into solid form and focus, to match the imagination or anticipation of the customer. So often there is that reality gap between promise and provision which has to be explained as to why it can't be done that way or at least in the time and at the price the customer wants to pay.Sometimes these confrontations can be fraught, as we are all pushed to tighter deadlines and budgets, but at the same time with the expectation of better quality and performance. Still the old adage remains -you can do it well, you can do it quickly or you can do it cheaply - chose any two but not all three.Sometimes these reality check moments produce real gems, what we could genuinely call a Homer Simpson moment, like the customer who wanted his company's round logo printed on a series of mugs for the office. When presented with the finished items he looked a bit puzzled."Why isn't it round?" He asked. Well it is round it's just wrapped round the curvature of a mug, I had to explain. That's just the shape of it. That still didn't satisfy him and you could see him still wrestling with this distortional dilemma. Now you realise you are dealing with someone who can only visualise what appears on a computer screen, where perspective can be visually created by software. It's only an illusion, of course, because, like a piece of paper, the monitor screen is still flat. Mugs are very definitely spherical objects, unless you get a posh square one from Ikea, and that won't go in a mug heat press.The only way to get a perfect appearance of roundness on a round surface would be by stretching the image to compensate for the curvature - much like sponsors logos are painted in perspective shapes on rugby pitches so they appear correct to the television lens. To do that you would need to know the mathematics of the mug, I just managed to remember enough O level trigonometry to bluff the customer with circumference calculations and the like to send him on his way in the knowledge that what he wanted to achieve was possible in the realms of physics, but beyond what he preferred to spend to achieve it.The correction of perspective in digital images is however one way of re-sizing originals to make them fit for printing. Particularly when going above A3 size to medium and large format printing, photographs that may have been cropped or generally chopped about may not fit a convenient paper or frame size.A lot of digital camera images are taken with what would traditionally be called wide angle lens settings - with the auto zoom set on the broadest angle. With compact-type cameras this is particularly noticeable as the lens in necessarily very close to the light receptors.

It is possible, with subtle use of the perspective tool in Photoshop, or a combination of any of the stretching software, to make an image fit a specific size without too obvious distortion. After selecting the whole image or turning it into a floating layer you can access these through Edit>transform to reveal a choice of options.In CS2 the Warp tool is especially good at pulling corners or parts of an image into a correct shape.Any camera lens will have some distortion, small or large, compared to what our eyes see and our brains interpret. A little bit of careful manipulation can sometimes produce a more pleasing result.At a very basic level, on sorting out the size of a digital photograph for printing, it is important to check the original resolution first. As people are so used to viewing pictures now on screens, laptops or even mobile phones they have very little concept of resolution. All digital cameras shoot at 72 dpi and that is monitor resolution so they look fine. It's only when you try and enlarge them for printing, or incorporate them in other documents that problems occur.For printing any digital camera image, at whatever size, it's always best to advise the customer to bring the picture as taken directly from the camera, not sized or edited, so it's the best possible original. Even if the customer knows what they are doing, it's still all too easy to make a mistake.While megapixel cameras now take 72 dpi picture potentially A0 plus in size, that is still only an A4 in reality at 300 dpi print resolution. If the original has been cropped down to fit a particular print size, it will of course be smaller still. I have learnt the hard way to get into a routine of first check resolution and size, resample, and then edit. That way you know what you are dealing with, whatever the customer has told you.For large format printing it isn't completely necessary to have a 300 dpi A1 or A0 as you will be dealing with a 200 or 400 mb file. This size will clog up some printer rips and leave you twiddling your thumbs and wondering whether you sent anything down at all.I only save my fine art clients files at this size for Giclee printing. This gives me a huge amount of colour information if I need to make subtle changes in colour hue to suit different media.Normal posters and general stuff I save at fifty percent size or at 150 or 200dpi. With a high resolution inkjet print there is no perceptible difference.The one catch is that if you are juggling images of different resolutions, be careful if you are using Photoshop as the master document. Whereas design packages like In Design and Quark will accept the dimensions of an imported file, size for size, Photoshop, being pixel based will adjust size in relation to the master. So a 72 dpi image dropped into a 300 dpi one will be less than a quarter of its original size.Such a drastic alteration in scale is likely to be obvious, but small variations where a customer may have saved at 250 or even 304 dpi will make a difference if real size is important. What you see may not be exactly what you get.Resolution variance is becoming more common as customers have files saved now over a number of years, and where their experience and expertise on the computer may have improved with the passage of time.A disk with a portfolio of digital images however may contain ones captured, edited and saved, at different points of the learning curve. It is important to remember that the combination of resolution and size is a vital equation in the colour management of pictures. Now there is no single original negative, files may have been saved and resaved, resampled and sized, and subject to all manner of mysterious manipulation before they come to be reprinted. Often you will have a customer absolutely certain in their own mind that you are printing exactly the same file as before, but with different results that they cannot explain.Invariably it is that it has been resaved, particularly through Jpeg compression, and that vital colour information has been lost. Resaving that lost file as a Tiff won't magically bring back those colours even if the customer tries to convince you it should.A really useful aid on our side with digital camera images is the EXIF data which is embedded with every picture taken. Unless it has been specifically overwritten, this will contain a lot of useful information about when the original was taken, when modified, and even camera settings.This invaluable resource can be accessed in most versions of Photoshop through File>File info Exif data.It's the digital equivalent of the smoking gun and has enabled me to turn the tables on customers' claims several times.Always remember if all else fails, baffle them with science!